Lease Commitments - Schedule of Weighted Average Remaining Lease Terms and Discount Rates (Details)	Mar. 31, 2022
Weighted average remaining lease term (years):
Operating leases	6 years 7 days
Financing leases	4 years
Weighted average discount rate:
Operating leases	4.02%
Financing leases	2.66%
PNM
Weighted average remaining lease term (years):
Operating leases	6 years 2 months 23 days
Financing leases	4 years 1 month 6 days
Weighted average discount rate:
Operating leases	4.03%
Financing leases	2.62%
TNMP
Weighted average remaining lease term (years):
Operating leases	2 years 9 months
Financing leases	3 years 11 months 4 days
Weighted average discount rate:
Operating leases	4.00%
Financing leases	2.71%